SIP Pros and Cons

People have high expectations for SIP. They hope it will enable advanced, anywhere, anytime multimedia communication. However, SIP is basically just another call control protocol, with its pros and cons. The following sections list a few of each.


  • SIP works independently of the type of session, or the media used, giving it flexibility.
  • It is an open standard, allowing multivendor support and integration. Applications can be written to customize SIP uses.
  • SIP messages are clear text, making troubleshooting easier.
  • SIP can accommodate multiple users with differing capabilities. For instance, in a conference that has some users with video capability and some only with audio capability, the video users can see each other. They do not have to drop down to audio only, as with other protocols.


  • Processing text messages puts a higher load on gateways. The router must translate that text into a language that the router can understand. Code for this must be in the Cisco IOS.
  • SIP is a fairly new protocol, so fewer people understand it than the older protocols. Be sure you have trained support personnel if you intend to implement SIP within your network.
  • When you are using both SIP and SCCP phones on the same network, you must convert between in-band and out-of-band DTMF tones.
  • SIP features are still being developed, and many vendors have proprietary implementations of the protocol.

Part I: Voice Gateways and Gatekeepers

Gateways and Gatekeepers

Part II: Gateways

Media Gateway Control Protocol


Session Initiation Protocol

Circuit Options

Connecting to the PSTN

Connecting to PBXs

Connecting to an IP WAN

Dial Plans

Digit Manipulation

Influencing Path Selection

Configuring Class of Restrictions

SRST and MGCP Gateway Fallback

DSP Resources

Using Tcl Scripts and VoiceXML

Part III: Gatekeepers

Deploying Gatekeepers

Gatekeeper Configuration

Part IV: IP-to-IP Gateways

Cisco Multiservice IP-to-IP Gateway

Appendix A. Answers to Chapter-Ending Review Questions


Cisco Voice Gateways and Gatekeepers
Cisco Voice Gateways and Gatekeepers
ISBN: 158705258X
EAN: 2147483647
Year: 2004
Pages: 218 © 2008-2020.
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